"One is that it’s not a coincidence that we normally
associate renting with larger structures rather than
single-family homes. The logistics of landlording are much better
in multi-unit buildings.

The second is that the biggest gluts of foreclosed
properties aren’t where the demand for living space is. New
rental housing in Phoenix, Las Vegas, or Tampa doesn’t help
relieve the razor-thin vacancy rates in New York, Portland,
Minneapolis, or San Jose."

So what would help the rental market? Yglesias says
new construction might work, but unfortunately that takes time
and bypassing invasive construction laws. Also, the renters
desperate for affordable rental space probably don't have time to
wait.